This invention relates to circular saws of the type comprising a table, a pivot member on the table and a saw assembly pivoted about a pivot axis with respect to the pivot member, whereby the saw assembly carrying a motor driven blade can be plunged into a workpiece supported on the table.
Such saws are known and described in published patent documents such as EP 0133666 and EP 0450400. These saws are useful and have numerous possibilities for enhancement to improve the capacity, capability and efficiency, not to mention cleanliness and safety of their arrangements. On the other hand, all these features add complexity and cost, and may render the saw user-unfriendly.
Both EP 0133666 and EP 0450400 mentioned above describe saws in which the saw assembly comprises an upper guard and a lower guard for the blade. The upper guard is formed from or on the housing of the assembly and permanently covers a top part of the blade. A bottom part of the blade is covered by the lower guard, but this must be withdrawn in use so that the blade is exposed when required to perform cutting operations.
A handle is disposed on the upper guard or housing by means of which a user can pivot the saw assembly up and down to perform cutting operations on a workpiece supported on the table.
The lower guard may be opened entirely by an actuating lever disposed on the handle. Alternatively the guard may be opened automatically by pivoting of the saw assembly, there being provided a connection between the guard and the pivot member for this purpose. A further alternative is that the guard may be opened partly by either of these arrangements and only further opened by direct contact with a workpiece. None of these is ideal or covers every desirable eventuality. In particular it is desirable only to open the guard as much as is necessary to cut the workpiece and no more, otherwise the dangerous blade is needlessly exposed. In any event, it is desirable (and, indeed, essential in some jurisdictions) to provide the following two safety features: first, a lock on the lower guard so that it cannot be manipulated open except by proper operation of the saw; and second, a lock on the saw assembly so that it cannot pivot down from a rest position except by proper operation, involving a release of the lock.